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Executive Summary

Throughout the 2011 fall semester we have been analyzing the Pioneer 1074 Easy Arc Staring Chainsaw. The fact that it is an older model makes it hard to find a model to compare it with. Prior to the dessection, our group members had very little working knowledge or a small gas engine, however as each gate was completed our knoweledge progressed. We also examined the impact that the four factors had on the products design and the manufacturing processes. One of the major points that can be taken away from this project is the importance of technical communication. The delivery and format of the report is just as important as the dissections and reassembly. Our group as a whole had many issues with this in the beginning of the project but as the gates progressed our technical writing skills improved greatly. We also learned the importance of time management. During the early gates, we would usually put things off to the final day. Towards the end of the project, we would start early and finish early. The fact that we did not rush the report help use organize our thoughts better and gave us better results.

Gate 1: Project Overview

Work Proposal

The following section will describe the process that will be used to disassemble the product. It will be crucial to stay organized during this process so that parts and components of the chainsaw are not lost. The group has decided to record the process of disassembly so that we have a history of where parts belong for the reassembly. The group has recognized the reassembly as the most challenging task due to the specific details required to put the subcomponents together. We anticipate that disassembly should not take more than one or two meetings, but do expect there to be some delays as we do not know exactly how complex the product truly is. Therefore some changes to the disassembly process may need to be made as we are working. Also in this section, we will discuss the strengths and weaknesses of each group member and discuss some possible issues we may have and skills we will need to develop.

Disassembly Process

Remove the exterior shell from the chainsaw. This will include removing the outer casings, the handles and the chain bar and will expose many of the main components. This process should not take more than one brief meeting.

Once the exterior shell is removed there will be various sub-components of the chainsaw exposed. The group will then proceed to remove the interior casings and some of the main components. These main components will include the exhaust, the flywheel, and the clutch. This process should take around an hour and can be accomplished in one group meeting.

Following step 2, the engine block and its connecting parts will need to be removed. This will include the carburetor, the choke, and the spark plug. Removing these parts should take between a half hour to two hours maximum and may be done in one group meeting.

The final steps to our disassembly will be to separate the two inner casings and remove the center shaft. This will allow the piston to be removed from the engine block and will expose the piston ring on the piston itself, and the trigger system. After this step, all components will be removed. This part of the disassembly should not take more than an hour and will also be accomplished in one meeting time.

Some tools we expect will need in order to dissect our product are as follows: a flat head screwdriver, an adjustable wrench, a socket wrench, a crescent wrench and possibly a rubber mallet. As we disassemble our product, we may come upon parts that need unexpected tools and we propose to have an extensive tool kit with us before we begin in case this occurs.

It will be important to keep connecting pieces together along with any fasteners needed to secure those parts. After dissection, we will need to reassemble our product and as mentioned above, we have recognized that this will be much harder than the disassembly.

Group Members

Name

Strengths

Weaknesses

Mohamed Abdulla

-Quick Learner -Strong Leader

-Lacks Dissection Experience -Poor Technical Communication

Zaccarie Peone

-Formatting Ability -Fast Worker

-Procrastinates -Lacks Technical Knowledge

Brendan Lewis

-Has Dissection Experience -Has Technical Knowledge

-Has a Busy Schedule -Lacks Expert Computer Skills

Sydney Sawyer

-Revision Expert -Excel Experience

-Poor Public Speaking -Poor Time Management

Management Proposal

Our group plans to manage our work by having regular meetings to work on the project, that may be dissecting the product, analyzing the different components, or writing technical reports. This section will discuss when and where meetings will be conducted, along with a conflict resolution plan. We will also propose a role for each group member and describe the responsibilities of each position.

Meeting Plan

The group will meet on Tuesdays and Thursdays. Meetings will be held at 3:30pm in the study lounge located on the first floor of Greiner Hall. Every member is expected to attend these meetings because no one has clas at these times. Additional meetings on weekends will be scheduled as necessary, and will be decided upon as a group. If members cannot attend these additional meetings because of other conflits, at least 3 members must attend for important decisions to be made.

Conflict Resolution Plan

Should any conflicts arise, we will speak openly as a group about the issue and propose solutions. We will then vote on the proposed solutions and in the case of a tie, an instructor will be contacted if a solution cannot be agreed upon. Also if a more serious issue arises an instructor will be contacted immediately.

Roles & Responsibilities of Group Members

“Project Manager”- Mohamed Abdulla

Responsibilities:

Ensure deadlines are met.

Allocate tasks to group members.

Set up mutually convenient meeting times.

Make sure project is going as planned.

Resolve conflicts between group members.

“Technical Expert”- Brendan Lewis

Responsibilities:

Have a basic understanding of subsystems and how they operate.

Understand how to carry out dissection process.

Use prior knowledge to help the group understand the product's functionality

“Communication Liaison” -Sydney Sawyer

Responsibilities:

Keep track of meetings and who attends.

Record group accomplishments.

Keep track of photographs and videos taken.

Keep in touch with instructors.

Communicate problems that may arise to instructors.

"Head of Research and Development” – Zaccarie Peone

Responsibilities:

Organize step by step dissection process.

Record important information that is obtained.

Have an understanding of product background.

Research product in order to reduce group uncertainty.

Point of Contact

In the event that any issues arise, or if you need to contact the group, please contact Sydney Sawyer, "Communication Liaison".

Contact Information:
sydneysa@buffalo.edu

Time Management Proposal

Figure 2 shows the proposed time layout for the project. The gates are colored in blue. Each gate is broken up into individual parts, these are colored in red.

Figure 2: Proposed time layout

Product Archeology

In the following section, a pre-dissection analysis will be conducted. The following profiles will briefly outline the history of the product, how it's used, the types of energy used, the complexity of the product, and the materials used. We will also compare it to similar existing products.

Development Profile

The chainsaw that was assigned to our group was manufactured by Pioneer Saws LTD in Peterborough, Ontario. It was manufactured between the years 1976 and 1982[2]. The main global concern at the time of manufacturing was the oil crisis[3]. Following the Isreali-Eygptian conflict, OPEC placed an embargo on oil, which caused engineers to frantically work to design energy efficient products. This product was intended to be sold in well-developed regions such as Europe and North America. One reason we know this is because it requires gasoline and oil to run, and both of these are not cheap. This tells us that it is intended to be sold in economically sound countries or regions. We can also get a lot of information from the main function of the product. Since it is intended to cut down or remove branches of trees, it is safe to assume that it was not meant for desert areas such as most of Africa, or cold weather climates such as Russia and Northern Canada, due to the fact that there isn't much plant life in these areas. Also, outside of first world countries it may be more socially unacceptable to cut down trees, but this is just an assumption. The intended impact of the chainsaw on the consumer is to reduce the amount of labor needed to complete tasks that involve substantial amounts of cutting. Before the invention of the chainsaw, removing unwanted limbs or whole trees was much harder and required a lot more effort and manpower. Using products such as an ax or a saw would take much longer and would put a lot more strain on the body. Having a chainsaw will make cutting wood much easier and less time consuming.

Usage Profile

We believe our product is intended for home use due to the fact that it is very simple. There are not any special features and the product itself is very easy to use and does not require a lot of maintenance. It does not take any special or extensive knowledge to use the product, one must only hold down the trigger and the chain starts spinning. The main function of our product is to cut wood. This may be to cut down whole trees, to remove unwanted or dead branches or to cut up large logs into smaller pieces. It should not be used for cutting metal because this would damage the chain and most likely break may other parts of the chainsaw.

Energy Profile

A chainsaw has various sub-components that transfer energy from one form to another. Figure 3 is a flow diagram which shows how each component works together to transfer and transform energy throughout the system.

Figure 3: Component Flow Diagram

As Figure 3 shows, there are five main types of energy used in the function of our chainsaw. They are mechanical, chemical, mass, magnetic induction, and electrical energies. The chainsaw mainly uses mechanical energy (red arrows in Figure 3) and the starting energy is mechanical energy provided by the user pulling the cord to pull start the chainsaw. The pull start will then turn the clutch and the crankshaft which will in turn begin the firing of the combustion reactions. The clutch is also the main connection between the engine and the chain. The clutch transfers mechanical energy through the sprocket to the chain which spins due to rotational mechanical energy. The clutch is also the main link to the engine; it provides the mechanical energy for the piston to begin its cycle.

The initial pull start and trigger system also provide mechanical energy to begin spinning of the flywheel. Although the main function of the flywheel is to cool the engine, the energy transfer plays a part of its function of providing electrical energy to the magneto, which is essential. As shown on the right hand side of Figure 3, the magneto provides energy to the spark plug via magnetic induction. With this magnetic energy, the spark plug can provide the spark to ignite the fuel mixture via chemical energy. With the combustion of the fuel, it will expand and therefore provide mechanical energy yet again to the piston to continue its cycle.

The only mass flow energy begins in the gas tank. The gasoline moves to the carburetor where it is combined with air and this mixture is then passed to the engine where it will be ignited. As stated above, this ignition of fuel provides mechanical energy to the piston which provides mechanical energy that will eventually lead back to creating the rotational energy of the chain.

Complexity Profile

As compared to other engines and engine systems, chainsaws utilize not only the simplest type of engine (two-cycle) but the simplest of engine components as well. As far as two-stroke engines come, the chainsaw uses the most simple of two-stroke engine designs but it also allows for optimal performance for the job that chainsaws will need to perform. Our chainsaw has six main components and they include the following: The engine, the carburetor, the clutch, the magneto, the flywheel and the ignition.

The engine: As stated above, our engine is a two stroke engine which is the simplest type of engine. Also since our chainsaw does not require large amounts of power output, this also leads up to believe that it is relatively simple. Also for this reason, our engine does not have to be very large and it only has one piston. The engine is where the main combustion and rotational energy reactions occur. It is also where the other components outside the engine meet to allow the product to perform. The sub-components within the engine include: a piston, spark plug, exhaust, reed valve, crankshaft, and combustion chamber. These units work together to perform the main functions of an engine: produce a driving force, rotate the crank and bring in new gas while excreting exhaust. The crankshaft attaches the engine to the clutch.

The centrifugal clutch: The clutch is the link between the engine and the chain. The clutch is not very complex due to the fact that it is only composed of three sub-components, an outer drum, a center shaft and weights[5] but its function is very important. The outer drum spins and is connected to the sprocket, which ultimately spins the chain-teeth around the guide bar which will be doing the cutting. The weights that are located inside the drum are connected to the center shaft by springs. When the engine begins to spin the center shaft and weights spin as well. At high speeds the weights force outward and centripetal force attaches them to the drum wall thus interacting with the drum/sprocket/chain system. These interatcions are most complex when the user lets the throttle go. At this point the engine idles and the spring pulls the weights off the drum wall and the engine can remain on, while the chain remains still.

The carburetor: In order for the engine to work it needs gas combustion. The carburetor is quite complex because it must precisely mix the air and gas so the engine can run. This system is made up of four main components that allow it to function: a tube, which is essentially the carburetor itself, a throttle plate, a venturi, and a jet[6]. The venturi creates a vacuum and the jet is the component that allows the vacuum to draw this fuel in. Lastly, the throttle plate is the air flow regulator, which gets air from the intake. The tube is where the final product of air and gas vapors all mix. This component gets much more complex when you break down the parts that allow functioning under certain circumstances such as the choke plate which allows idling and starting the engine cold.

The spark plug: This gas/air mixture will do nothing without the spark plug igniting it creating the combustion. The spark plug itself is not very complex, in that it only produces a spark, but its interaction with its energy source, the magneto, is quite complex energy from the magneto. The magneto creates the electrical charge needed to fire spark. The magneto is made up of magnets and coils that work like an electrical generator[5]. It then sends out periodical surges of charge which is then converted into sparks by the spark plug.

The flywheel: The functions of the flywheel are very simple but also important. The flywheel spins to suck in air for the carburetor and it cools off the engine. The combustion within the chamber produces a lot of heat that can lead to damaging affects if not cooled. Lastly, it contains the magnets for the magneto and is connected to the crankshaft.

The pull-start ignition: Directly connected to the crankshaft through the clutch, is the pull-start ignition. It is quite simple and it works with a simple spring loaded pulley and essentially manually rotates the crankshaft firing, off the combustion reactions.

Material Profile

There are several materials that are clearly visible on the exterior of the chainsaw. One of them is the aluminum casing that conceals the chainsaw's interior. Another material that can be seen on the exterior is a plastic casing that covers the top section of the chainsaw. The exterior of the chainsaw is held together by steel bolts and nuts. The blade that is currently without a chain is made of steel. The wiring on the inside of the chainsaw will be copper wire with rubber tubing protecting it. The engine block and its connecting components will most likely be made of aluminum due to the fact that there is high heat produced in the engine and these parts will need to stand up to the high temperatures. The flywheel is also composed of aluminum because aluminum is not a magnetic material and due to the fact that the flywheel transfers magnetic charge to the magneto, using a metal that is magnetic would disrupt this function. We assume that many other components inside the chainsaw are made of aluminum because it is relatively cheap and light weight, and since using plastics during the 70s and 80s were still a very new technique, it is safe to say that not many plastic parts are included. We also know that the center shaft will most likely be made of cast iron due to the fact that it will have to endure high vibrations from the engine and will need to be very strong.

User Interaction Profile

The user interaction with the Pioneer Easy-Arc chainsaw is quite simple. In order to operate the chainsaw the product must be filled with gas and oil in their respective compartments. The fuel-oil ratio in our product is 16:1[2]. These compartments are located next to each other on the side of the chainsaw. Our product is quite easy to use, especially for those who have used outdoor equipment before. The user only needs to hold down the trigger when they are going to cut something and exert a downward force to move the chain through the wood. When the cutting is through, the user will let go of the trigger and flip the on/off switch to turn the product off.

To begin the start up process, one hand must be properly holding the chainsaw with one finger over the trigger. The other hand must be used to pull the cord to begin the ignition. The start up is a small-scale representation of a lawn mower. The interface of the chainsaw is designed with simplicity in mind, making start up simple. This may be hard for some people who are not used to this type of start up procedure or those who cannot pull the cord fast enough to start the engine.

There is very little maintenance required for the owner of our chainsaw. The user will need to refill the gas and clean or replace the oil when necessary. Both of these are rather simple and only require the necessary lid to be unscrewed. No tools are required for this maintenance. The other necessary maintenance the consumer must perform is to replace the chain when it gets dull. Chains can be bought at any home improvement store and sometimes a worker at the store can even replace the chain for the consumer. If the consumer was to replace the chain themselves all they would need is a flat head screwdriver. Two flathead screws hold the blade protector in place. One must simply remove the screws, remove the dull chain and replace it with the new chain. Other maintenance that may be necessary for our product would be necessary due to excessive or improper use. If a part breaks or cracks it would need to be replaces, but this generally does not happen if the product is used correctly and these things may be covered by a warranty provided by the producer.

Product Alternative Profile

Image 1: Black & Decker Alligator Lopper

One alternative to our product is the Black & Decker Alligator Lopper (shown in Image 1). The Alligator Lopper can be used for pruning tree branches or cutting them into more convenient sections. The Black & Decker Alligator Lopper runs on electricity. This would make the Alligator Lopper less expensive in the long run because there is no need to continuously pay for gas. Also, there would be no harmful emissions that the Pioneer Easy-Arc chainsaw produces. Running on electricity could also be a disadvantage because the consumer would have to deal with the power cord. This would limit the reach of where in a consumer’s yard the product can be used, since it must always be near a power source. The Alligator Lopper weighs only 6.5 pounds and is therefore very easy to control and can be used by a wider range of consumers. Compared to the Pioneer Easy-Arc chainsaw the Black & Decker Alligator Lopper would be much safer. There is no kickback on the Alligator Lopper like there can be on a chainsaw. Although the Alligator Lopper can be safer, it can’t cut down branches larger than four inches in diameter. Because of this the Alligator Lopper can’t cut down large trees and branches like the Pioneer Easy-Arc chainsaw can. Since our product is from the late 70s to early 80s it is hard to determine the exact price in today’s economy but the Black & Decker Alligator is less than $100[1]. To compare these two alternatives one really needs to look at the specific job. If the customer wants to use the product for pruning branches or cutting down a relatively small tree, the Black & Decker Alligator Lopper would be a much better choice, but if the consumer needs to cut a large branch or log or cut down a large tree, the Pioneer Easy Arc chainsaw would be the better choice as compared to the Alligator Lopper.

Image 2: An ax

Another alternative to our chainsaw would be an ax as shown in Image 2. An ax can also be used to cut a tree, but it would take much more time and effort. The main advantage to using an ax is that it is much cheaper. An ax costs anywhere between $20-$50 and does not need any gas or electricity which also reduces its overall cost to the consumer. The only maintenance needed is to sharpen the blade when it gets dull. Another advantage is that the ax is very light weight weighing only a few pounds and it is easy to use. It does not take any extensive knowledge to use and it is fairly safe as long as the user stays away from the sharp edge while cutting. The main disadvantage is that it is very strenuous. To cut down a whole tree with an ax would take a lot more effort than using a chainsaw and the user could potentially pull or strain a muscle using the product. It would also take much longer if someone was using an ax. A chainsaw is a much quicker method than an ax and does not require as much energy from the consumer. If the consumer is only cutting a small tree, or cutting up pieces of wood, then an ax would be the better choice, but again if the user is cutting down a large branch of tree a chainsaw would be most effective.

Gate 2: Product Dissection

Project Management

Preliminary Project Review

Overall, our project management plan has been successful thus far. Each individual has fulfilled their duties assigned to them in Gate 1 and the responsibilities seem to fit each individual well. Our Project Manager has made sure we stay on track with the assignments and made it clear when additional meetings are being held. Our Technical Expert did an outstanding job during dissection due to his prior knowledge of small gas engines. His knowledge of the individual components and their inner-workings were useful throughout the dissection. Thus far our management plan has been fairly successful, however we have had some difficulties.

Project Management Challenges

As a group we have run into several challenges that were not accounted for in our project management plan. One of the challenges we have faced is our difficulty finding times for meetings in which everyone can attend. This challenge has left us short members for several meetings. We have made sure to keep our schedules clear on days that we have agreed upon for regular meeting times. Additional meetings are sometimes hard to coordinate and may still be a challenge in the future. The assigned role of Head of Research and Development has proved to be slightly unimportant and there has proved to be little research required through the first two gates. As a group we have decided to add to the responsibilities of Wiki Expert to this role giving this group member more responsibilities. This will help evenly distribute the work required for each member. This new role will include posting our work onto the Wiki page and help other group members with difficulties they may have dealing with the Wiki. Also, we will be adding to the role of Communication Liaison. Along with communicating any problems to instructors and keeping track of the meetings and what goes on, we will add the responsibilities of Technical Writer. This role will include revising and editing all technical writing.

Dissection Plan Review

Overall our dissection plan was a failure. Although our general outline provided in gate 1 was successful in guiding us through the dissection it was not nearly complex enough. We were not prepared for the complexity of the chainsaw once the exterior shell was removed. The plan we had in place did not take into considerations of the challenges we would run into. One of these challenges was the removal of the sparkplug. We were unaware that a specific tool was required to do this process. This required us to have to obtain new tools to continue the dissection. Although the removal of the spark was a challenge we found the remaining parts to be relatively easy to disassemble. Another challenge we were faced with was the organization of the dissection. With the chainsaw containing many small parts we were not prepared with how they should be organized once they were disassembled. We were forced to make many decisions on the fly throughout the dissection process. A better plan would have been useful in preparing us for the dissection. We will make sure we are more prepared for the following gates.

Product Archaeology

In this part of the project, our chainsaw was dissected analyzed part by part. In the sections below we will provided the step by step process used to dissect the chainsaw. Following the dissection process, we will discuss the component connections as well as why they were implemented the way they were. We will also include a brief discussion of how the four factors influenced the design of the components.

Difficulty Scale

Above is our definition of a "Difficulty Scale". A "1" is the least difficult, and a "4" is the most difficult.

Dissection Process

Steps 1-6

Figure 4 describes the first 6 steps of the dissection process.

Image 3: Chainsaw following step 5

Image 4: Chainsaw following the first 6 steps

Image 5: Heat Guard referred to in step 9

Image 6: Clutch referred to in step 11

Image 7: Carburetor referred to in step 14

Image 8: Engine Block referred to in step 16

Image 9: Center Shaft referred to in step 16

Image 10: right casing referred to in step 16

Image 11: left casing referred to in step 16

Figure 4: Steps 1-6 of the Dissection Process

Once steps 1-6 are complete, the exterior will be completely removed. This will reveal many of the main components of the chainsaw such
as the carburetor, muffler and the engine. The steps above were not too difficult. Once the screws are located, there should not be too much difficulty removing the parts. As you can see step 6 was ranked the most difficult, and this was mainly due to the time consumed during the step. It is important to remove the On/Off switch before removing the engine guard. This step will save you time, and prevent you from damaging the product.

Steps 7-19

Figure 5: Steps 7-19 of the Dissection Process

Once steps 7-19 are complete, the chainsaw will be completely dissected. These steps were a little more challenging than the first 6 steps due to the complexity of the components removed. The challenges and resolutions are listed below:

The first challenge the group faced was removing the clutch. Initially, the group attempted to remove the clutch with an adjustable wrench. However, the center shaft, which holds the clutch in place, began to rotate when the moment was applied. In order to compensate for this rotation, a counter moment was applied to the center shaft. This prevented the additional rotation, and the clutch was removed fairly simply. During this step, you must exercise precaution in order to prevent damage to the clutch, and center shaft.

The next problem the group faced was the removal of the spark plug. We had the proper tool to remove it (spark plug socket wrench), however a great amount of force was required.

A third problem was encountered when we attempted to remove the carburetor/choke. In order to remove the carburetor, we had to disengage the choke. The choke is mounted between the frame and the carburetor. Initially, we attempted to force the choke out without using any tools. After this method failed, we realized that the choke was screwed into the carburetor. The conflict was resolved by removing these screws and disengaging the choke cable from the exterior frame.

Splitting the interior casing was the final challenge that the group encountered. The problem here was the complexity. The casing, engine and center shaft were conjoined. In order to split the casing we needed to remove the screws that held the engine. Contrary to what we expected, we were not able to remove the engine just yet. The engine was connected to the center shaft which was lodged between the two pieces of the interior casing. We then split the casing and removed the right side. The left side was still attached to the center shaft. A rubber mallet was used to remove the center shaft.

Was the Part Meant to be Removed?

While analyzing each part of the chainsaw, the question "Was this part meant to be removed by the consumer?" was asked for each part. The table below summarizes the results of this analysis.

Part

Was it meant to be removed

Supporting Evidence

Clutch Cover

Yes

The clutch cover was held in place by flat head screws. If this part was not meant to be removed, it might have been welded to the body.

Fly Wheel Cover

Yes

This part was also held in place by flat head screws.

Air Filter/Cover

Yes

This part was also held in place by flat head screws.

Handle

Yes

This part was also held in place by flat head screws. Also this part may need to be replaced some time in the future.

Chain Bar

Yes

This part was also held in place by flat head screws. Also this part may need to be replaced some time in the future.

Engine guard and On/Off Switch

Yes

The engine guard was meant to be removed. It is held in place by simple screws. The on/off switch is threaded and held in place by a nut. This part may need to be replaced and is clearly meant to be removed.

Muffler Cover

Yes

In order to clean the muffler this part needs to be removed. This part is held by simple flat head screws and is fairly easy to remove.

Muffler Head

Yes

This part was held in place by a couple of screws. It was relatively easy to remove it .

Heat Guard

Yes

This part did not require any tools. It was obviously meant to be removed.

Flywheel

No

This is may be intended to be removed my a mechanic while doing repairs, however it does not seem as if it is intended to be removed by the consumer due to the fact that a great amount of force is required to remove it.

Centrifugal Clutch

No

This part was not meant to be removed due to the fact that so much force was needed in order to remove it. (Refer to fig. 5 Part 11)

Spark Plug

No

In order to remove the spark plug a special tool was needed (spark plug socket wrench). We also needed to apply a great amount of force to remove it.

Choke

No

In order to remove the choke, you need to disengage the choke cable, and remove the screws that attached it to the carburetor. Therefore we have concluded that this part was not meant to be removed.

Carburetor

No

In order to remove the carburetor, the choke needs to be removed. Since the choke is not meant to be removed, we concluded that the carburetor was not mean to be removed.

Metal Spacer

No

In order to remove the metal spacer, the carburetor must be removed.

Casing/ Center Shaft/ Engine

No

A great amount of force was exerted when we split the casing. This gave us the notion that this part was not intended to be dissected.

Throttle Cable

No

Given the fact that the throttle cable is located between the left and right casing, and the fact that we said the casing was not meant to be removed, we concluded that this part was not meant to be removed.

Battery

Yes

This was held in place by a couple of flat head screws, and may need to be replaced in the future.

Piston/Crankshaft

No

Despite the fact that no tools were required to remove the crankshaft, we concluded that this part was not meant to be removed because of the fact that the left and right casing would need to be split.

Performance & Connections (Reasons for Location)

Figure 15: Functional Model of a Chainsaw-shows the energy (physical/translational/and rational) and material flow of the connections

This figure shows what components are connected and the function of each connection. It labels why each function must be connected in order to perform the overall function of the product. A further detailed description of the arrangement and reasons for the implemented connections in comparison to the overall performance is explained below.

The chainsaws sub-systems are arranged in such a matter that each system can interact with one another for optimal performance. Optimal performance for our product can be considered as an engine running at full throttle. When the throttle is wide open the chain will be rotating at full velocity and we will achieve optimal cutting performance. Thus we need quick rotation and easy transfer of energy within a compact product small enough to be held and maneuvered.

Image 12: Top View of the carburetor/throttle system

➢ Keeping compactness in mind, systems have to be close but equally important is efficiency. The centrifugal clutch, crankshaft and flywheel are the three components that transfer the combustion energy into ultimate chain rotation that we are looking for. These parts are located directly in line with one another, conjoined by the center shaft which also must be located such that it holds almost everything together. This linear alignment allows all three components to rotate in sync with one another, which allows a decrease in energy loss through each connection (figure 15: #9 shows these energy tranfers). If this wasn’t the case massive amounts of energy would be lost in gear friction, heat, and in unnecessary material. Similarly, negatively affecting the compactness and lightweight product we are after.

➢ The flywheel is on opposite sides of the clutch for multiple reasons (figure 16 shows the flywheel on the left and clutch on the right). The flywheel is connected to the pull start and when starting the engine it would be dangerous to put the pull start right next to the saw blade. Also, another job of the flywheel is to cool the combustion chamber so location nearest the chamber as well makes sense for optimal cooling. Finally the flywheel contains the magnets for the magneto. Thus the magneto, which is fixed by bolts to the side of the engine, is located below and to the right of the flywheel (refer to figure 6). The magneto/flywheel system can’t be adjacent to the rotating chain because it is magnetic and could potentially hurt the performance of the chain rotation or the effectiveness of the magnet (function of magneto is labeled in figure 15). The magneto is also located in a spot that allows it to be wired electrically to the spark plug without having to get too complicated with wiring. The spark plug is screwed directly into the engine. The function of the spark plug is to ignite the combustion gas, so it would make sense that the location of the spark plug would be right outside the combustion chamber.

➢ The sprocket/chain system is located at the right side of the engine and is also lined up directly with the flywheel/crankshaft and connected via the clutch. This location was implemented under the assumption that most people are right handed. Having the blade to the right puts the handle to the left, which is meant to be gripped with the left hand and is used for precision and support. This leaves the throttle handle in the rear, meant to carry majority of the load and manipulate the throttle with the statistically stronger right hand.

➢ The engine is what produces our rotation and is the center where all the sub-components meet to achieve the overall function (refer to figure 15). Thus the engine is located centrally in comparison to the sub-components. It is connected to all the sub-components via the inner casing and a series of screws and fuel lines. It is placed directly behind the clutch/flywheel/crankshaft system because after the combustion reaction the energy will be transferred directly and linearly to the crank again trying to get the energy to transfer to the sprocket as directly as possible. In comparison to the overall product the engine is located towards the rear. This is better than the front because it is easier to support the engines heavy weight distribution, especially for a product that must be held and easily manipulated. Located off of the engine is the exhaust (figure 16 shows the exhaust behind the clutch) and the exhaust will be placed precisely at the bottom of the pistons stroke and opposite side of the intake port. This is important because in order to get new combustible gas into the chamber the waste gas must be excreted (refer to figure 15). The waste must be forced out opposite of the intake through the export. Therefore, the exhaust cannot be adjacent to the carburetor import so the waste product does not compromise the efficiency of the chainsaw.

➢ The carburetor is located on top of the engine (refer to figure 7). This is a practical, convenient, and possibly an inefficient location. It is connected to the engine through a port, to the choke by screws, to the throttle by a cable, to the gas tank through a fuel line and to the product via screws directly into the casing. It is practical because in relation to the engine it is the best/most direct route to import the combustible gas to the chamber. It is convenient because the air filter must filter the air going into the carburetor. The air filter is a component that the consumer will need to change from time to time; therefore an accessible location is desired. Similarly coming off of the carburetor will be the choke. The choke must be adjacent to the carburetor because the choke allows the extra air flow during start. This is something that will as well need to be accessed every time before starting, which again the top of the product being the most convenient location for easy access. The gas tank is located below the carburetor and the carburetor must connect to the tank via fuel lines in order to vacuum gas out of the tank. This may not be the best location and may be something to consider changing for it goes against gravity which may mean gas at the bottom of the tank could potentially be wasted, but we will look into further modifying the product in the proceeding gates.

As you can see the location of one component is interrelated to the location of another in some way. One can’t talk about the location of just one component without needing to mention multiple other components since each part affects the next directly. By moving one component of the product won’t just disturb the equilibrium of that one part but will affect the system balance of the entire product. System balance in the overall product is important in order to obtain an efficient, smooth running product. Taking into consideration that this is a chainsaw the product itself is going to produce a lot of vibration which is why the connections are very important as when taking into consideration of performance.

"Four Factor" Analysis of Product Design

Global Factors

The Chainsaw is designed to be used in areas where gas and oil are readily available. This will make the intended area for the chainsaw to be predominately in developed countries. The tools used to dissect the product are available internationally not limiting it to one specific region. Any geographic location where a chainsaw would be required would be an ideal location for use.

Economic Factors

The chainsaws exterior and frame is composed of mainly metal material. The use of metal for the chassis is much different from what you would find today. Chainsaws are now made of mainly plastic exterior, which would help lower the cost and weight. This is an economical design factor when trying to design a product for different types of consumers. Such as, a professional may want something more rugged such as steel but still lightweight considering the frequent use. A homeowner would be looking for something predominately lightweight and cheap.

Societal Factors

Figure 17: Standard warning label seen on today's chainsaws.

There are many societal impacts that deal with our product. One main area is safety. Chainsaws can be lethal if used incorrectly, and that is why it is important that a side handle is used to help support the weight of the chainsaw. Another societal factor or lack there of for our chainsaw is a warning label for liabilities. Seeing that our chainsaw was made in the 1970’s liability issues were not as predominant as they are today. As you can see in the figure 17 today’s chainsaw are issued with warning labels that will cover any liabilities stemming from improper use. Our chainsaw does have any warnings on its chassis.

Environmental Factors

There has been a drastic change from the time of production of our chainsaw, 1970s to our current time in regulations over environmental impact. One major change in legislation was the Clean Air Act of 1900, which allowed the EPA to regulate internal combustion air pollution in small gas engines. A chainsaw which is considered to be a class 5 engine is now subject to regulation in its emission such as particular matter, air toxins, and oxides of nitrogen. Although there was a Clean Air Act passed in 1970 its only goal was to regulate Major Hazards to human welfare. This regulation did not deal with small gas engines[7].

Gate 3: Product Analysis

Project Management: Coordination Review

Cause for Corrective Action

General Issues

After finishing Gate 2, we have solved many issues that were mentioned, but we have also come across some new ones. We have all made sure to keep our schedules open on Tuesday and Thursday afternoons for our regularly scheduled meetings. One scheduling issue we have is trying to find times to meet on weekends. Some of the members have jobs and work on the weekends, and with other class assignments and homework, it can be hard to get everyone together. The past two weeks have been particularly hard to get together and get work done because each member had multiple exams to prepare and study for, along with other assignments. Another issue we have with meetings is that two of our members live on campus and two are commuters. This becomes an issue when meeting times on weekends are scheduled at the last minute, considering that the two commuters have to drive to campus. We also have a communication issue between our members. There have been multiple occasions where a meeting time was agreed upon and some members were considerably late or members were not notified of the meeting times until the last minute. In the future, we will all try to communicate better either by email, text or phone call and be on time to meetings.

Another issue we have come across is that some of our members get easily distracted by things like sports and video games. There have been multiple times when the group has met and not gotten anything done because of this. We will talk about this as a group and discuss how we can work better together. Our Technical Expert has really stepped up and become a leader. He always tries to make sure that meetings are efficient and that the work gets done. He is always good about setting up meetings and communicating with the other members. We propose that he and the current Project Manager become Co-Managers. One problem we have come across while splitting work between members is that one person working on a specific part of the assignment may think that it sounds clear to them in their head but that doesn’t mean the words on the page can be understood by someone else. Since we have lost points for this before, we will be sure to have at least one other member of the group read over what we have done and make sure that it is clear and understandable.

Dissection/Reassembly Review

After realizing that our chainsaw was much more complicated than we originally thought, and after our first dissection was unorganized and practically a failure, we decided to put it back together and do the dissection again. Following the first dissection we had many screws, nuts, bolts, etc. that we were unsure exactly where they belonged. The second time we dissected the chainsaw, we made sure to take pictures of multiple steps and parts, while keeping screws, bolts and nuts together with their respective parts. Our second dissection clarified the roles of many components as well as the overall performance of the chainsaw. This will also help with reassembly because we better perspective on where parts belong.

Future Issues

One issue we expect to come up in the future is time management. With Thanksgiving coming up, we know that it will be difficult to accomplish anything during the upcoming weeks. With members going home or on vacation, we are unsure when we will all return to Buffalo. This becomes problematic because Gate 4 is due the week after we return. Also, with the semester coming to an end soon, we must begin preparation for our final exams. It will only get harder to meet and get work done due to the fact that we will all have studying or other major assignments to work on. We plan to deal with this by keeping up with our communication and trying to get a majority amount of the work done when the remaining assignments are given and not waiting until the last minute, which has been a problem for us in the past.

Product Archaeology: Product Evaluation

Below, we have analyzed each component of our chainsaw carefully and determined the engineering decisions made during the design process. We have also label the complexity of each component based on geometry, and interaction complexity. We define component complexity and interaction complexity in table below. Table 1 shows our scale of component complexity, while Table 2 shows our scale for interaction complexity.

Table 1: Component Complexity Scale

Table 2: Interaction Complexity Scale

Fly Wheel Cover

Image 13: Fly Wheel Cover

Function:
Provides Protection for the Flywheel by completely covering it and ensuring that it is not exposed. Also houses the mechanism which retracts the pull start rope. It operates in the environmental conditions of the surroundings, as it is located on the exterior of the chainsaw. This component exhibits energy flows once the chainsaw is started in the form of vibrations.

Number of times Used:
Once

Shape:
The Fly wheel Cover is not symmetrical. It is 3 dimensional, and is shape the way it is in order to completely cover the flywheel.

Weight:
10 oz-1 lb

Materials Used:
The frame is composed of aluminum. In order to withstand great vibrations, this part must be composed of a strong metal.This material was chosen with economic and societal factors in mind. Aluminum is light and inexpensive. The fact that it is light reduces the overall weight of the chainsaw. The rope is made of synthetic fibers while the handle is made of plastic. Economic factors were considered when designing these parts. Synthetic fibers and plastic are inexpensive.

Aesthetics:
The fly wheel cover needs to look appealing due to the fact that it is visible on the exterior of the chainsaw. It is painted yellow in order to match the rest of the chainsaws exterior. That being said, aesthetics were definitely taken into consideration during the design process.

Manufacturing Methods:

Manufacturing Process- Die Casting

Reason for process- Die Casting the casing components will provide a strong, dimensionally accurate part that can be produced in high volumes. Tap drilling was used in order to provide the cover with threads for screws. Economic Factors influenced the decision of using die casting since the high volume production will be cover the high initial cost.

Material Selection- Aluminum was used to manufacture the flywheel cover since it is a durable material that is ideal for die casting.

Effect of Shape- The flywheel cover like similar casing components has no part geometry and therefore makes it and ideal product to be Casted. Complex shapes can be molded to make what would be a complicated manufacturing processes simple.

Component Complexity:
2

Interaction Complexity:
1

Clutch Cover

Image 14: Clutch Cover

Function:
Provides Protection for the Clutch, as well as the user by completely covering ther clutch and ensure that it is not exposed.It operates in the environmental conditions of the surroundings, as it is located on the exterior of the chainsaw. This component exhibits energy flows once the chainsaw is started, in the form of vibrations.

Number of Times Used:
Once

Component Shape:
The clutch cover is not symmetrical,and is 3- dimensional. The reason why it is shape this way is so it will be able to fully and effectively do its function, that is completely cover the clutch.

Weight
14 oz-1 lb

Materials Used:
The clutch cover is composed of Aluminum. This material was chosen with economic,and societal factors in mind. Aluminum is light and inexpensive.

Aesthetics:
The clutch cover needs to look appealing due to the fact that it is visible. It makes up a part of the chainsaw exterior, this is why it is painted yellow. Aesthetics were definitely taken into consideration during the design process.

Manufacturing Methods:

Manufacturing Process- Die Casting

Reason for process- Die casting will allow the clutch cover to be produced in high volumes with high dimensional accuracy. Tape drilling was used in order to apply threads for screw holes. The use of this process was influenced by economic factors since the high volume production will cover the initial cost to make the molds. There is evidence of flash and parting lines that show evidence to the use of this process.

Material Selection- - Aluminum was used for the Clutch Cover since it is a light metal and is ideal for die casting.

Effect of Shape- The clutch cover much like the main casing needs to be fastened to another component so high dimensional accuracy is important. The shape having no part geometry is best manufactured from a pre-made mold so that production is simple.

Component Complexity:
2

Interaction Complexity:
1

Air Filter Cover

Image 15: Air Filter Cover

Function:
Houses the air filter. Also covers the carburetor and the choke. Prevents debris from entering the intake system.It operates in the environmental conditions of the surroundings, as it is located on the exterior of the chainsaw. This component exhibits energy flows once the chainsaw is started in the form of vibrations. It also exhibits a slight amount of mass flow, as air passes through the filter.

Number of Times Used:
Once

Component Shape:
This part is symmetrical along both axis, is rectangular, and three dimensional. It is shape this way because it needs to fit into its place and cover the intake system

Weight:
3-5 oz

Materials Used:
This component is made of plastic. The reason why plastic is used is because it does not have to withstand great vibrations. Plastic is the more economic choice.

Aesthetics:
Aesthetics needed to be considered in the design process. This part has a nice finish due to the fact that it on the exterior of the chainsaw. It is dyed green in order to complement the yellow.

Manufacturing Methods:

Manufacturing Process-Injection Molding

Reason for process-Injection molding is commonly used in the manufacturing of plastic components with uniform wall thinness. The Air Filter Cover would need to be produced in high volumes, which would cover the initial cost needed to create the molds. There is evidence of flash and parting lines that show evidence to the use of this process.

Material Selection-A plastic polymer was used for two reasons. One was since it is located on the top of the chainsaw and does not require the strength of the other exterior components, plastic is much cheaper to use in production. The second reason is that plastic is ideal for injection molding.

Effect of Shape-The Air Filter Cover has a simple design with consistent wall thickness making this process ideal for injection molding. Other then that factor there is no other impact the shape plays on the process.

Component Complexity:
2

Interaction Complexity:
1

Engine Guard

Image 16: Engine Guard

Function:
Covers the engine, also holds the on/off switch in place.It operates in the environmental conditions of the surroundings, as it is located on the exterior of the chainsaw. This component exhibits energy flows once the chainsaw is started, in the form of vibrations.

Number of Times Used:
Once

Component Shape:
This component has no symmetry and is shaped the way it is in order to completely cover the engine. It is very thin because it doesn't need to hold the engine in place, it only needs to cover it.

Weight:
6-8 oz

Materials Used:
The engine guard is composed of aluminum. Again, economic and societal factors were considered in the design process.

Aesthetics:
Aesthetics were considered in the design process. This part has a smooth finish and is painted yellow in order to match the rest of the exterior.

Manufacturing Methods:

Manufacturing Process- Die Casting

Reason for process-Die casting is ideally used for parts that have evenly distributed wall thinness, which need to be mass-produced. This process also allows for the product to be dimensionally accurate so that it can be fastened on to the other casing pieces securely. Economic Factors influenced the use of die casting since the high volume production will cover the instal cost to produce the molds. There is evidence of flash and parting lines that show evidence to the use of this process.

Material Selection- Aluminum was used for this process since it is an ideal metal for this process. Using aluminum also provides the chainsaw with a lightweight metal, which can cut down on the overall weight.

Effect of Shape-The component is simple in design and its shape really has no effect on the process used. The process was selected for more cost effective reasons.

Component Complexity:
2

Interaction Complexity:
1

Main Casing

Image 17: Main Casing

Function:
Houses the center shaft, crankshaft, and the piston. Also has threaded holes which hold the engine cylinder in place.It operates in the environmental conditions of the surroundings, as it is located on the exterior of the chainsaw. This component exhibits energy flows once the chainsaw is started, in the form of vibrations.

Number of Times Used:
twice (left casing and right casing)

Component Shape:
This component is symmetric, the left casing is identical to the right casing. It is shaped the way it is in order to secure the center shaft safely. The shape contours the internal components.

Weight:
1-1.5 lb

Materials Used:
This component needs to be able to withstand great vibrations. Sturdy material is needed. This is why it is made of dense aluminum. It is thick in order to account for these vibrations. Again economic factors were considered here. Aluminum was cheaper to produce than plastic in the 1970's that is why this product primarily consists of aluminum.

Aesthetics:
Aesthetics were considered in the design process. This part has a smooth finish and is painted yellow in order to match the rest of the exterior

Manufacturing Methods:

Manufacturing Process-Die Casting

Reason for process- Die casting is ideal for products that are being produced in high volumes. The part will need to have a high dimensional accuracy since it consists of two parts and will need to be placed together. Tape drilling was used to place thread holes for the screws. Economic Factors influenced the use of die casting since the high volume production will cover the instal cost to produce the molds. There is evidence of flash and parting lines that show evidence to the use of this process.

Material Selection-Aluminum is an ideal material for die casting and is a rather lightweight metal that would be ideal for the casing.

Effect of Shape-The shape being rather complex needs to be dimensionally consistent. Die casting allows a product to be mass-produced with consistency.

Component Complexity:
3

Interaction Complexity:
1

Handle

Image 18:Handle

Function:
Provides a spot for the user to hold and support the chainsaw. Also allows user to easily and accurately maneuver the chainsaw. It operates in a moderate environment environment and will only exhibit flows due to vibrations.

Number of Times Used:
Once

Component Shape:
The handle is bent into a U shape. The reason it is shaped this way is so it can be secured to the bottom of the chainsaw and come around the top, where it is intended to be held. This allows for complete control of the chainsaw. It's cross-section is circular in order to make it comfortable to hold in comparison to a rectangular cross section for example.

Weight:
6-8 oz

Materials Used:
This component is made out of steel unlike the other parts that were examined thus far. There is also a rubber grip where it is intended to be held. Societal factors were considered when selecting the material. Safety is a major factor. Steel is extremely sturdy and has a higher yield strength than aluminum. This will assure that there will be no deformations in the handle which may result in a horrible accident. Rubber is used as a gripping device. This will assure that there is no slippage while holding the chainsaw.

Aesthetics:
As Far as aesthetic are concerned, this is an exterior part and needs to contribute to the overall look of the chainsaw. The steel has a smooth finish and is rust-free.

Manufacturing Methods:

Manufacturing Process-Forging then Bent

Reason for process-Much like the Blade the handle is a thin piece of metal with uniform thinness that can easily be compressed; once the metal was compressed the piece was then bent into its current shape. This process was common for parts like this in the 1970’s. The rough corners are a sign that this process was used.

Material Selection- Aluminum is a low cost metal that can easily be shaped into its required shape. It would have been used to cut down on cost and weight. Aluminum can be forged

Effect of Shape- The shape of this piece is a main reason why this process was used. Since this piece has a uniform thinness and is essentially a straight piece of metal before it was bent, the compression force from forging easily creates this piece.

Component Complexity:
1

Component Complexity:
1

Chain Bar

Image 19: Chain bar

Function:
The main function of the bar is to hold the chain in place. The flows involved with the chain bar are vibrations given off from the rotation of the chain. The chain bar is located in a moderate environment that houses the chain as it rotates around.

Number of Times Used:
Once

Component Shape:
The chain bar is long and thin. The reason why it is shaped this way is to increase the reach of the chainsaw and to allow for a thin, and precise cut.

Weight:
6-8 oz

Materials Used:
The chain bar is composed of iron. The reason why iron was chosen in the design is because iron can withstand great vibration and a great driving force without snapping. That would be a societal factor of the design consideration as sturdiness effects the safety.

Aesthetics:
Again this an exterior part so it has a smooth finish. It is a shiny silver which helps contribute to the looks of the product.
Manufacturing Methods:

Manufacturing Process- Forging

Reason for process- Forging is ideal for parts that can be manufactured using compression forces. You can tell that this process was used by the rough edges visible on the bar. The method is rather old but since the chainsaw was made in the 1970’s the process would not of been considered old.

Material Selection-Iron was used for this component of the chainsaw since a metal is needed to resist the compression forces of forging. It provides the chainsaw with a sturdy arm to secure the chain around.

Effect of Shape-The bar has symmetrical geometry with a uniform thickness; using the compressive forces that forging provides the component was made. A piece with out that required a more complex design would not of been ideal for this process.

Component Complexity:1

Interaction Complexity:1

On/Off Switch

Image 20: On/Off Switch

Function:
Allows engine to start. Operates in a moderate environment on the exterior of the chainsaw. Associated with energy flow in the form of electricity.

Number of Times Used:
Once

Component Shape:
This component is finger sized. It is meant to be flicked by a finger therefore there is no need to enlarge it.

Weight:
2-3 oz

Materials Used:The on off switch is composed of aluminum. Again economic and societal factors contribute to the choice of material. Aluminum is light in weight and inexpensive. The wire is composed of copper and is insulated in a rubber wire. Copper was choice due to the fact that it is a great conductor with low resistance. Rubber was chosen with safety in mind. Rubber is a great insulator and will insure that the user does not get shocked.

Aesthetics:As far as aesthetics are concerned, this component has a nice smooth finish. There are two reasons why it was designed this way. The first is due to the fact that this part is visible on the exterior of the chainsaw. It contributes to the overall look of the product. The second is due to the fact that this part will be touched each time the chainsaw is used. This means that a smooth surface finish is needed in order for the user to comfortably use the component.
Manufacturing Methods:

Manufacturing Process-Turning

Reason for process- Turning is visible on this component due to its fine surface finish and lack of flash and parting lines. The threads located on this component could have also been added in one stage using this manufacturing process. This would of saved economic costs from having to make molds as well as turning to add the threads.

Material Selection- The choice of material came from economic factors dealing material not from manufacturing processes.

Effect of Shape-The shape is a major reason why turning was used to create this piece. Because of its circular design and symmetry the piece was easily made using the process.

Complexity:
1

Interaction Complexity:
2

Spark Plug

Image 21: Spark Plug

Function:
Provides the spark which allows the combustion reaction to occur. Operates in a moderate environment above the engine block. Associated with energy flow in the form of electricity.

Number of Times Used:
Once

Component Shape:
The spark plug is one of the smaller components in the chainsaw. The reason it is small is because the chainsaw only needs a small spark in order start the combustion reaction.

Weight:
2-3 oz

Materials Used:
The spark plug is composed of aluminum, copper and plastic. The copper allows for an efficient transfer of electricity. As stated earlier, copper is an excellent conductor. It is insulated with plastic in order to prevent the electric current from take the wrong path and possibly causing injury to the user. Its base is composed of aluminum. The reason why aluminum was chosen over copper here is the fact that aluminum is stronger. Conductivity is not needed at the base of the spark plug. As far as the four factors are concerned, societal factors were considered when designing this part. As you can see safety was in mind when choosing plastic to insulate the spark plug.

Aesthetics:
Aesthetics were not considered while designing this part. The spark plug is not visible to the user and does not contribute to the overall appearance of the chainsaw.

Manufacturing Methods:

Manufacturing Process-Injection Molding

Reason for process- The spark plug is made of a ceramic material that would have been made using a mold that was injected with a ceramic material. This process allows them to be produced in high volumes with dimensional accuracy to connected into its required location. The fine surface finish is a sign of this. Turning was used to apply thread lines.

Material Selection-The ceramic material was selected for reasons outside of the manufacturing process. Ceramic however can be used in injection molding.

Effect of Shape-Much like the material selection the shape played little role in the manufacturing method selected other then the shape could be used in the injection molding process.

Component Complexity:
2

Interaction Complexity:
1

Trigger

Image 22: Trigger & connecting rod

Function:
The trigger and connecting rod, when pulled opens the throttling device which will allow air to enter the intake system. It operates in a moderate environment as it is located on the chainsaws exterior. The flows associated with this part include mass flow, as it leads to air entering the intake system, as well as energy flow in the form of human energy (pulling on the trigger).

Number of Times Used:
Once

Component Shape:
The trigger is slightly curved at the end. The reason it is shaped this way is to allow the user to comfortably wrap his/her finger around it. This minor detail improves the quality of thee chainsaw dramatically. If it were not curved the way it was it would be slightly awkward to pull on. This concern was considered while designing the trigger. It is connected to a long thin rod which has a hook at the end of it.The reason why the rod is shaped this was is because it has to run down the handle of the chainsaw and hook on to the throttling device which is connected to the carburetor.

Weight:
2-3 oz

Materials Used:The trigger is composed of plastic. Plastic was chosen with societal factors in mind, primarily safety. Again Plastic is a great insulator and will insure that the use will not have to endure any electric shock. The rod is composed of aluminum. Aluminum was chosen due to the fact that it can undergo the tensile stress needed to perform its function. If plastic was used for instance, the rod will more than likely snap.

Aesthetics:
When considering the aesthetics of this component, the trigger is dyed black and has a smooth finish in order to contribute to the overall appearance of the chainsaw. The connecting rod however is not visible on the exterior therefore it is reasonable to concluded that aesthetics were not considered.

Manufacturing Methods:

Manufacturing Process-Injection Molding

Reason for process-The trigger being a plastic component can be easily shaped using injection molding which will allow it to be manufactured in high volume. The process was influnced by Economic Factors because of this high volume production. The fine surface finish as well as the appearance of flash and parting lines is a sign that this process was used.

Material Selection-The decision to use plastic for the trigger enabled injection molding to be used to for this part of the process.

Effect of Shape-The trigger has a simple shape that can easily be made using the injection molding process. The shape of the trigger came from societal influences from what the common perception of a trigger is.

Component Complexity:
1

Interaction Complexity:
2

Sprocket

Image 23: Sprocket

Function:
Transfers rotational energy from the clutch to drive the chain. The sprocket operates at high speeds and is associated with energy flow transfer.

Number of Times Used:
Once

Component Shape:
The sprocket has a circular shape meaning it has infinite lines of symmetry. It is a three dimensional part. It has a circular shape in order to be able to perform its function and rotate in a circular motion. It also has a hollow cavity which houses the clutch, and a built in gear which spins the chain.

Weight:
8-10 oz

Materials Used:
The sprocket is composed of steel. The reason why steel was chosen is due to the fact that this part will undergo tremendous vibrations. Steel is stronger than aluminum, so in this case the designers chose quality of cost. This is a societal factor because safety is considered when the designer wanted reliability.

Aesthetics:
It doesn't seem as though aesthetics were much of a concern when designing the sprocket. This part has a rough surface finish and does not have any paint. The reason aesthetics were not considered in the design process is due to the fact that the sprocket does not contribute to the overall appearance of the chainsaw. It is not visible on the exterior of the device.

Manufacturing Methods:

Manufacturing Process-Forging

Reason for process-Forging was used for this piece in order for the piece to be more durable. Forging will allow the piece to be much harder then die-casting. Societal Factors influenced this decision since the extra strength will make this piece much safer since this piece spins the chain.

Material Selection-Forging was used for this piece in order for the piece to be more durable. Forging will allow the piece to be much harder then die-casting. Societal Factors influenced this decision since the extra strength will make this piece much safer since this piece spins the chain.

Effect of Shape-The shape of this component is a result of the process used. Since it was forged the unique geometry visible on the sprocket is possible.

Component Complexity:
2

Component Complexity:
1

Metal Spacer

Image 25: Metal Spacer

Function:
The metal spacer has a built in washer which the clutch rotates on in order to reduce friction during the spinning of the clutch. It operates in a moderate environment as it is located on the exterior of the chainsaw, and will only exhibit flows due to vibrations.

Number of Times Used:
Once

Component Shape:
The metal spacer is relatively thin compared to the other parts of the chainsaw and does not have an axis of symmetry. The reason it is shaped this way is so it will require a small amount of material. It job can be done without taking much space up and by having a thin space, it effectively make the chainsaw thinner.

Weight:
4-6 oz

Materials Used:
This part is composed of aluminum. Economic factors were considered when choosing aluminum, again aluminum is inexpensive. A material of greater strength such as steel is not needed due to the fact that this part will not undergo great vibrations.

Aesthetics:
This part has a fine surface finish and is painted yellow in order to contribute to the overall appearance of the chainsaw as it is visible from the exterior of the product.

Manufacturing Methods:

Manufacturing Process-Die Casting

Reason for process-Die casting was used to create this piece because it requires consistent dimensional accuracy in order to connect to the rest of the frame. Economic Factors were considered manufacturing this part since it is a high volume component the high initial cost for this process will be covered.

Material Selection-Aluminum was used due to its high fluidity and its ability to be easily die-casted.

Effect of Shape-The components core design comes from factors outside of the manufacturing process. The die casting process however influenced the uniform walls on this component.

Component Complexity:2

Interaction Complexity:1

Throttle

Image 26: Throttle

Function:
Allow air to enter the intake system by opening a metal flap. This metal flap is opened when the trigger is pulled. The throttle operates in a moderate environment above the carburetor, and is primarily associate with mass flow while allowing air to enter the intake system

Number of Times Used:
Once

Component Shape:
The throttle has an axis of symmetry, and had an circular shaped inlet. The reason why the inlet has a circular shape is to maximized the air flow when the flap is opened. Circular inlets allow air to flow rather smoothly. Another reason why it is shaped the way it is is due to the fact that i needed to fit in its place above the carburetor.

Weight:
2-4 oz

Materials Used:
Aluminum is used for this part. Again economic factors were considered when choosing the material, aluminum is inexpensive and light weight.

Aesthetics:
During the design process aesthetics were taken into consideration . Only in this case, it was not due to appearance of the part, but rather it was due to the functionality. The choke has a smooth surface finish. The reason the design calls for a smooth surface finish is in order to increase the flow rate of the air entering the intake system.

Manufacturing Methods:

Manufacturing Process-Die Casting

Reason for process-This process was used in order to create consistent dimensional accuracy among the various pieces. You can see signs of flash as well as parting lines on the surface of the component. Economic Factors influenced the use of this process since the high volume production will cover the initial cost for molds.

Material Selection-Aluminum was selected due several factors. The manufacturing reason for its selection was its ability to be easily die casted.

Effect of Shape-Shape has no effect on the manufacturing process used the required design from this piece come from the components function.

Component Complexity:
2

Interaction Complexity:
1

Carburetor

Image 27: Carburetor

Function:
The function of the carburetor is to mix the gas from the gas lines and air which was brought in by the throttle, and send it to the combustion chamber. This part operates in a moderate environment above the engine block. The flows associated with the carburetor are primarily mass flows consisting of gasoline and air.

Number of Times Used:
Once

Component Shape:
The carburetor takes on the shape of a cube. It is three dimensional and is quite symmetric. It has a hollow, circular shaft running through the middle. The reason why this shaft is present for functionality purposes. This shaft the air and gas is mixed in preparation for the combustion. It also has a flap similar to the one present in the throttle. This flap opens up and allows the mixture to enter the combustion chamber.

Weight:
4-6 oz

Materials Used:
The carburetor is primarily composed of aluminum. Aluminum was chosen with economic facts in mind once again as it is inexpensive, and light weight. However upon further inspection you will note that the flap is composed of brass. Societal factors were considered in the design process when choosing brass. Once the air-gas mixture enters the combustion chamber, the brass can with-take the heat associated with the combustion. That being said this part was designed with safety in mind.

Aesthetics:
Aesthetics were not a big concern during the design process, however they were considered. The hollow shaft has a smooth surface finish which allows the air and gas to mix and flow smoothly. The exterior has rough finish and is not painted. This can lead the dissector to the assumption that aesthetics were not considered here. The reason they were not is due to the fact that the Carburetor is not visible on the exterior of the chainsaw.

Manufacturing Methods:

Manufacturing Process-Die Casting

Reason for process-The process was used because of Economic Factors. Since there is a high volume being produced the high initial costs for the mold are covered. You can see signs of flash left over from the process as well as parting lines. The holes visible for screws were added using tap drilling.

Material Selection-Aluminum was used here since it can be die casted easily as well as its usefulness in the components function.

Effect of Shape-The component consisting of 3 individual parts were die casted separately and then attached using screws. The shape of the carburetor required this process due to it rather complex design.

Component Complexity:
3

Interaction Complexity:
2

Magneto

Image 28: Magneto

Function:
The magneto provides the spark needed for combustion to the spark plug. The magneto operates in a moderate environment ans it is located on the exterior of the chainsaw. The flow associated with the magneto is an electric current generated by induction.

Number of Times Used:
Once

Component Shape:
This component is quite small and takes on a circular shape. The group has agreed that the shape does not effect the function of the magneto. However, the reason why it is small is because only a small spark is needed to create the combustion reaction.

Weight:
1-2 oz

Materials Used:
The magneto is composed of rubber. Rubber was chosen taking safety into consideration. Rubber is an excellent insulator,and with all the charge being created the insulation is needed.

Aesthetics:
Aesthetics were taken into consideration when designing this part primarily because it is visible from the exterior of the chainsaw. The rubber is dyed black and has a smooth surface finish. This contributes to the overall appearance of the chainsaw.

Manufacturing Methods:

Manufacturing Process-Injection Molding

Reason for process-The signs of injection molding are visible on the surface of the component with flash and parting noticeable. Injection molding would be ideal for this component economically since it is being produced at high volumes.

Material Selection-The material was selected for reasons outside of the design process. Manufacturing decisions did not factor into the selection of rubber.

Effect of Shape-The shape of the magneto made it an easy selection for injection molding due to its uniform wall thickness and simple geometry.

Component Complexity:
1

Interaction Complexity:
1

Crank Shaft

Image 29: Crank Shaft

Function:
Transfer energy created by combustion, and the piston to the center shaft where it is then converted to rotational energy. The crankshaft operates in a harsh environment and undergoes many vibrations. The flow associated with the crankshaft is the conversion of translational energy from the piston to rotational energy used by the clutch to eventually drive the blade.

Number of Times Used:
once

Component Shape:
The crank shaft is a long rectangular piece. It is 3-dimensional, and it has a greater thickness along the horizontal axis than it does along the vertical axis. The idea behind increasing the thickness along the horizontal axis is to increase the moment of inertia, which eventually leads to an increase in compressive and tensile strength.

Weight:
12-14 oz

Materials Used:
The center shaft is composed of cast iron. Cast iron was chosen for feasibility reasons. The crankshaft will undergo tremendous vibrations as well as compressive and tensile stress. It is much stronger than aluminum, and is also a bit more brittle than aluminum. The fact that the center shaft is brittle and strong will prevent deformation and failure. So strength is the primary reason why cast iron was chosen.

Aesthetics:
Again, aesthetics were not taken into consideration during the design process. The crankshaft has a rough surface finish, and no paint. It is not visible from the exterior and will not contribute to the overall appearance of the chainsaw.

Manufacturing Methods:

Manufacturing Process-Die Casting

Reason for process-Die casting was selected since it was the best choice economically. In order to produce this component in such high volumes this was the most feasible process. Signs of this process can be seen all over the surface with flash and parting lines being visible in many places.

Material Selection-The material used for this piece was selected due to the components function instead of the manufacturing process that was required to make it.

Effect of Shape-The shape of the crankshaft was ideal to be die casted. A mold to create this piece can easily be made.

Component Complexity:
3

Interaction Complexity:
2

Piston Ring

Image 30: Piston Ring

Function:
Seals the combustion chamber, prevents gas from leaving the chamber. The piston ring functions on in a hot environment attached to the piston. The piston ring contains mass flow from exiting the cylinder.

Number of Times Used:
Once.

Component Shape:
The piston ring, as the name suggests takes on a circular ring shape. It is three dimensional, however it is very thin and my be modeled as a 2-dimensional component in an analysis problem. The reason it is shaped this way is because it need to fit in a thin groove in the piston.

Weight:
1-2 oz.

Materials Used:
Aluminum was used because it is light weight and inexpensive. No special metallic properties are needed to perform its task, and therefore economic factors mainly contribute to the choice of material.

Aesthetics:
Aesthetics were not a huge factor in the design of this component, however it does have a nice smooth finish. The reason why it has this smooth finish is because the ring needs to touch the cylinder wall. The fact that the ring is smooth reduces the friction between the two and eventually increases the efficiency of the engine.

Manufacturing Methods:

Manufacturing Process-Pressed

Reason for process-This process is used since it is very simple to have done the small piston ring was made easily by being pressed from a piece of metal. Using this process is very cost effective for a piece this size.

Material Selection-Using aluminum is a cheap effective product to press into the given ring like shape.

Effect of Shape-The shape is very important for the manufacturing process used. Since the part is so small it can easily be pressed into the desired shape.

Component Complexity:1

Interaction Complexity:3

Choke

Image 31 : Choke

Function:
When the engine is first started, a very rich air/fuel mixture is required because cold fuel vaporizes slowly. The choke at the top of the carburetor provides the richer mixture by closing and choking of the carburetor's air supply. The choke functions in a quite environment outside of the chainsaw. The flow associated with this component is a mass flow by mixing the fuel.

Number of Times Used:Once

Component Shape:The choke is a long slender piece with a circular platform at the top. The reason for this platform is so the user has a place to push the choke in. The choke is three-dimensional, and has has vertical symmetry.

Weight:
1-2 oz

Materials Used:
The choke is composed of a plastic base, with a rubber platform. The reason why rubber was chosen for the platform was for safety reasons. Again rubber is an excellent insulator and will prevent the user from experiencing an electric shock. Plastic was chosen for the base because it is a small part that does not undergo many vibrations.

Aesthetics:
Aesthetics were considered when designing the choke. It has a smooth finish, and is dyed black. These features were added in order to improve the appearance of the chainsaw, as well as increase the comfort of use.

Manufacturing Methods:

Manufacturing Process-Injection Molding

Reason for process-The choke switch being a plastic component can be easily manufactured in high volumes using this process. This process is the most cost effective for this piece.

Material Selection-Plastic was used due to its low cost and ease during the injection mold process.

Effect of Shape-The shape played little role in the manufacturing process due to its simplicity injection molding was a simple process to use to create the component.

Component Complexity:1

Interaction Complexity:1

Flywheel

Image 32 : Flywheel

Function:
The flows associated with this component is the conversion from translation energy from the pull start to rotational energy, which gets the rotation of the clutch started for the piston and center shaft. Also acts as an inter cooler for the engine and provides magnetic charge for the magneto. The fly wheel interacts in an environment directly inside the main casing it is a rather mild environment.

Number of Times Used:
Once.

Component Shape:
The flywheel takes on a circular shape with long slender blades protruding from its surface. The circular shape, along with the evenly distribute weight allows for an easy rotation. The blades are present in order to have somewhat of a "fan effect" which helps cool the engine.

Weight:
8-10 oz

Materials Used:
The flywheel is primarily compose of aluminum, but also has a couple of magnets lodged in. Aluminum is used for the flywheel for two main reasons. First off and most importantly, aluminum is not a magnetic metal. With the flywheel transferring magnetic charge from one component to another, it wouldn't make sense for the flywheel to be compose of a magnetic material. It would effect it ability to spin freely. Out of all of the non magnetic metal, aluminum is one of the most inexpensive. That was taken into consideration when the designer choose the material.

Aesthetics:
Aesthetics were not taken into consideration with this component as it is not visible on the exterior, and does not need to have a certain surface finish in order to function.

Manufacturing Methods:

Manufacturing Process-Die Casting

Reason for process-This piece is different from other pieces that use this process. The flywheel is a rather complex component. Investment Casting could of have been used to create this component however since it is being produced in high volumes and molds are not re-usable die casting is a much more feasible process when looking at Economic Factors. Tap drilling was used in order to apply threads to the flywheel.

Material Selection-The use of aluminum again comes from outside factors, since it is a light metal it reduces the overall weight of the chainsaw. Though the aluminum does allow for a complex shape to be molded due to its properties.

Effect of Shape-Flywheels usually has a pretty defined shape and the decision to use a casting process because of it comes from cost and time. Like already stated since the product is being produced in high volumes it is best to use a mold to manufacture the flywheel at a fast pace.

Component Complexity:4

Interaction Complexity:3

Heat Shield

Image 33: Heat Shield

Function:
Shields the exhaust and relieves it of heat rejected by the engine. The component functions in a hot environment above the engine. The flow associated is a heat transfer from the engine to the heat shield.

Number of Times Used:
Once.

Component Shape:
The heat shield takes on the shape of a square and is rather thin. The reason why is is square shape is because it has to fit in its place on to of the engine.

Weight:
Negligible

Materials Used:
Aluminum was used for the heat shield with economic facts being considered. Aluminum is inexpensive and light weight.

Aesthetics:
Aesthetics were not really considered here. It is not visible on the exterior of the chainsaw. However it does have a fine surface finish which can be accredited to the manufacture process used, which is forging.

Manufacturing Methods:

Manufacturing Process-Forging then Bent

Reason for process-The heat shield is a thin piece of aluminum that has been bent into shape. The compression forces from forging will create the thin piece of metal with a uniform thickness. This process was a lot more common in the 1970’s, which is why it would have been used.

Material Selection-The reason to use aluminum over another material comes from a factor outside of the manufacturing process. Aluminum however can be used for forging.

Effect of Shape-Since the heat shield has a uniform thickness forging becomes a viable option. The shape makes it a feasible forging metal that can then be bent into shape so that I can cover the vital parts of the engine.

Component Complexity :1

Interaction Complexity :2

Exhaust

Image 34: Exhaust

Function:
Removes unneeded mass from the cylinder and ejects it into the surroundings.It operates in a moderate environment due to the fact that the heat shield prevents a majority of the heat from reaching the exhaust. The flow associated with the muffler is the mass flow as mass is ejected to the environment.

Number of Times Used:
Once

Component Shape:
This component is square shaped and has a connecting tube, which connects it to the engine. The reason why it takes on this shape is so it can fit in its place below the engine and come around to the side of the chainsaw.

Weight:
4-6 oz

Materials Used:
The base of the muffler, which is connected to the engine is composed of aluminum. The reason aluminum was used here is because it is inexpensive and can absorb any remaining heat from the heat shield. The Muffler cover is composed of iron in order to prevent any damage taken by misuse.

Aesthetics:
Althought this part is visibel on the exterior of the chainsaw, aesthetics were not considered here. The muffler is rusted and has a rough finish to it. The reason why aesthetics were bypassed can go back to the components function. This part is meant to remove waste, and will most like become filthy sooner or later.

Manufacturing Methods:

Manufacturing Process-Die Casting

Reason for process-Using Die Casting for this process allows the piece to be consistently manufactured so that it can lock into its required position. Since the chainsaw was mass-produced this component like any die casted component will cover the initial cost during the manufacturing. Parting lines can be seen that show the use of this process. The thread holes were applied by the tap drilling process.

Material Selection-Aluminum was used like many other parts of the chainsaw since it has a lower cost that most metals and is ideal for the die casting process.

Effect of Shape-The shape of this component plays little role in the manufacturing process. It is simple enough to where a mold could be made to replicate the piece so it can be produced in high volumes.

Component Complexity:2

Interaction Complexity:1

Engine Block

Image 35: Engine Block

Function:
The engine block where combustion occurs. The combustion which takes place in the engine block eventually causes the piston to move. The engine block functions in an extreme environment in the center of the chainsaw. The flows associated with this process are heat transfer, and combustion to translational. The flow from this component allow the main function of the chainsaw to occur.

Number of Times Used:
Once

Component Shape:
The engine block takes on a square-type shape with ridges all around the exterior, and a hollow shaft running down the center.The purpose of the ridges is to increase the surface area which will prevent overheating. The hollow shaft houses the piston and basically makes up the "piston-cylinder system" for combustion.

Weight:
Light

Materials Used:
Aluminum was used to manufacture the engine block. Economic factor and societal factors were considered when choosing aluminum for this part. Aluminum is inexpensive and light weight. The light weight of the engine block eventually leads to the chainsaw itself being lighter.

Aesthetics:
Aesthetics were not considered while designing this component. It has a rough finish with parting lines visible, and also does not have any paint on it. The reason why aesthetics where not considered is because this part is not visible from the exterior of the chainsaw.

Manufacturing Methods:

Manufacturing Process-Die Casting

Reason for process-The engine being made of aluminum is ideal for die casting since it is mass-produced. The initial high cost would eventually be regained in the fast high volume production of the piece. You can see flash and parting lines across the surface.

Material Selection-The material being aluminum is ideal for die casting however the manufacturing process was the not reason for the use of aluminum.

Effect of Shape-The engine block is not the most simple in design but using a mold to create the piece will allow it to be mass-produced much faster then other manufacturing processes would allow.

Component Complexity:4

Interaction Complexity:3

Piston

Image 36: Piston

Function:
Expands and compresses gases in the cylinder while transferring energy to the crankshaft which is physically connected to the piston. The Piston operates in an extreme environment at a high temperature. The flows associated with this part include the energy conversion of combustion energy to translational energy as the piston moves.

Number of Times Used:
Once

Component Shape:
The piston takes on the shape of a cylinder primarily due to the fact that it needs it fit in its place in the engine block. Its face is flat and smooth, which is needed in order to compress the gas in the engine.

Weight:
2-4 oz

Materials Used:
Aluminum was used to manufacture the aluminum. Economic factor and societal factors were considered when choosing aluminum for this part. Aluminum is inexpensive and light weight. The light weight of the piston eventually leads to the chainsaw itself being lighter, as well as an increase in cycles it can undergo.

Aesthetics:
Aesthetics were not considered while designing this component, however it has a smooth surface finish. This reduces the amount of friction between the piston and the cylinder, and increase its ability to compress the gas.

Manufacturing Methods:

Manufacturing Process-Die Casting

Reason for process-The engine being made of aluminum is ideal for die casting since it is mass-produced. The initial high cost would eventually be regained in the fast high volume production of the piece. You can see flash and parting lines across the surface.

Material Selection-The material being aluminum is ideal for die casting however the manufacturing process was the not reason for the use of aluminum.

Effect of Shape-The engine block is not the most simple in design but using a mold to create the piece will allow it to be mass-produced much faster then other manufacturing processes would allow.

Component Complexity:2

Interaction Complexity:3

Nuts

Table 3: Nuts Removed from Chainsaw

Function:
The function of the nut is to secure the bolts and screws in place. They exist in many different environments across throughout the chainsaw. The nuts themselves are not associated in any flows however they do allow the flows of the rest of chainsaw functions to occur by ensuring that the connections are implemented.

Manufacturing Methods:

Manufacturing Process-Forming

Reason for process-This process is used because its not only the most cost effective however safest for manufacturing the nuts. Since the nuts hold the entire chainsaw together they must be strong using forming hardens the nut. Tap drilling was used in order to add the threads on the bolts.

Material Selection-The nuts are made from steel since it is a strong metal that will not deform easily over time. The steel is selected for its strength and not because of the manufacturing method that is used to make them.

Effect of Shape-The shape of this component allows it to be manufactured using forming.

Flat/Hex Head Screws

Table 4: Flat Head Screws Removed from Chainsaw

Table 5: Hex Head Screws Removed from Chainsaw

Function:
The function of the screws are similar to that of the nut. The screw interacts with nut to hold the chainsaw in place the screw is inserted while the nut holds it in place. The environment they are located in is throughout the chainsaw varying from mild to extreme temperatures. The screws are not associated with any main flows, however they do allow for the chainsaws various flows occur.

Manufacturing Methods:

Manufacturing Process-Forming/Forging

Reason for process-Forming and Forging are used to create the screws since the create a much stronger and harder product then one such as die casting. This is influenced by societal factors. The body of the bolt is made by forming while the threads are added using forging.

Material Selection-Steel is selected because it is much stronger and harder then other metals. This is required because of societies concern for safety. The manufacturing process does not influence the material selection.

Effect of Shape-The shape of the screw has been the same for years the left over material from the initial forming process is used to create the head. The shape must be consistent for safety.

Solid Modeling

Below are the solid models of three parts. The parts we chose were the Chain Bar, the Sprocket, and the Clutch. We chose to model these parts because they are key components to the function of our product. They allow the chain to move and therefore remove material. These connections are also simple in geometric shape and were therefore much easier to model. We used AutoDesk Inventor to model our parts. We were advised to chose this program because we lack experience in three dimensional modeling and we were told this would be the easiest program to learn how to use. We chose to use a front and back view of the Sprocket due to it's intricate design on both sides.

Engineering Analysis

There are many factors that must be considered when designing a product. In this section we will break down the three main sub-functions of our chainsaw; conversions of fuel into a combustible material, conversion of a combustion reaction into rotational energy and conversion of physical human energy into rotational energy. In doing this, we will focus on the factors that were taken into consideration during the design process. We will also conduct an analysis problem on the second sub-function using the seven step analysis approach.

Conversions of fuel into a Combustible Material

In order to convert gas, which is our main source of energy, into a combustible fuel, we need the carburetor and the engine to work together. The following factors were considered during the design of this sub system:

Environmental:

The carburetor produces a chemical mixture that will be ignited to form a combustion reaction. The waste product that is formed must be excreted from the product. According to the environmental protection agency (EPA), small internal combustion engines contribute 5 percent of the total man made hydrocarbons in ground level ozone formations. In 1995 the EPA established a regulation which divides engines into classes based on whether they are handheld or non-handheld and on engine displacement/size. Classes III, IV, and V are for handheld equipment such as chainsaws. EPA Phase II standards became effective in model year 2002 for engines in classes III and IV and in 2004 for class V and have to become EPA and CARB certified based on these standards specified on the website[9].

Economic:

A typical problem in two stroke engines is the chemical mixture produced by the engine is not always used up all the way and a lot of unburned gasoline is excreted. To increase efficiency we can consider a more efficient igniting system or spark plug. The idea behind it would be to somehow ignite all the gas quickly and efficiently so you will generate more power with less gasoline. To do this we could consider a different material for the ignition. Ultimately maximizing efficiency and being able to charge extra for a greener product.

Societal:

Based on the regulations above and the possible changes to the engine, not only will it be good for the environment but good for the market. People in general are health and environmentally conscious in today’s day and age, so a product that is exercising health and safety regulations while improving efficiency and saving the consumer money will be very good on the market, which is something companies and engineers are taking into consideration today; that people would rather have an environmentally friendly product.

Conversion of a Combustion Reaction into Rotational Energy

In order to convert the combustion reaction within the engine block to rotational energy in the sprocket the piston, crankshaft, center shaft, and centrifugal clutch must work together. This subsystem was designed with the following factors in mind:

Environmental:

In this subsystem minimizing friction between each component is the best way to maximize energy loss, thus maximizing efficiency. We can potentially minimize friction by using certain production techniques that leave a better surface finish. The piston and engine block should be forged for two reasons. One, because it will harden the steel used that will have round surfaces. Also, it will leave a glossy surface finish which is needed. If the piece is turned tiny scratches will be left which will produce high amounts of friction with such a high speed piece.

Societal:

This subsystem of the engine is what produces massive amounts of vibration in the product. High amounts of vibration for a long period of time can produce great strain in joints and muscles and can vibrations can physically harm someone, especially a professional over a long period of time, or a casual user who had an accident do to these high vibrations. It is important to have smooth connections and symmetry in components to allow easy/smooth transfer of energy

Global:

Depending upon where you live noise might be an issue. If you are a professional, noise is not something you’re worried about, but for household projects an engineer may consider loudness of the product for residential areas. We can assume that residential users aren’t going to need the same power as a professional so one may consider using a smaller engine and/or spending more on comfort and less power. So a weaker yet lighter frame could be used so it is more comfortable to use. We can do this by injection molding a frame with plastic rather than a steel die casted frame.

Analysis problem

Below we will analyze the efficiency of this subsystem. Efficiency is define as the ratio of the translational work out and the amount of heat provided by the combustion reaction.:

Problem Statement:

The 2 stroke engine of the Pioneer 1072 Chainsaw has a power output of 1 kW. Determine the efficiency (ε) of the engine given a specific fuel consumption (listed below). Figure 18 represents a simplified schematic of the thermodynamic process of a heat engine, which can model our chainsaw's engine.

Diagram:

Figure 18: A block diagram showing the thermodynamic processes of an engine.

Assumptions:

The engine is considered a heat engine. This is necessary because the following equations are specific to a heat engine.

The fuel has a heating value of 44,000 kJ/kg (qHV). This quantity is necessary in the equations mentioned below.

The fuel has a density of .74 g/cm3 (ρ). This quantity is also necessary in the equations mentioned below.

Some heat is lost to a low temperature sink. This is important because not all the heat provided from combustion is used in the engine. Some heat always has to be lost.

Our chainsaw has a fuel consumption of 6.5 L/hr (Vfuel)

All fuel will be combusted. This is important because we are assuming that no fuel is wasted and that all of it is converted into usable heat.

Equations:

𝑚𝑓𝑢𝑒𝑙= 𝜌∗𝑉𝑓𝑢𝑒𝑙

This represents the equation to obtain the mass flow rate from the volume flow rate using the density of the fluid.

𝑄= 𝑚𝑓𝑢𝑒𝑙∗ 𝑞𝐻𝑉

The mass flow found by using the above equation will now be used with the heating value of the fuel to find the heat produced by combustion per second.

𝜀= 𝑊𝑜𝑢𝑡𝑄

The general definition of efficiency is outputs over inputs. So in our case, the efficiency of our engine is the total power output (Wout) over the heat produced from combustion (𝑄).

Calculations:

.74𝑔𝑐𝑚3∗1 𝑐𝑚310−6𝑚3∗1 𝑘𝑔1000 𝑔∗1 𝑚31000 𝐿= .74 𝑘𝑔/𝐿

6.5𝐿ℎ𝑟∗ 1 ℎ𝑟3600 𝑠=1.806𝐸−3 𝐿/𝑠

𝑚𝑓𝑢𝑒𝑙=.74𝑘𝑔𝐿((1.806𝐸−3)𝐿𝑠)

𝑚𝑓𝑢𝑒𝑙=1.336𝐸−3 𝑘𝑔/𝑠

𝑄=(1.336𝐸−3𝑘𝑔/𝑠)∗(44,000𝑘𝐽𝑘𝑔)

𝑄= 58.8 𝑘𝐽

𝜀= 1 𝑘𝑊58.5 𝑘𝑊

𝜀= .017

Solution Check:

𝑚𝑓𝑢𝑒𝑙= 𝜌∗𝑉𝑓𝑢𝑒𝑙

𝑘𝑔𝑠=𝑘𝑔𝐿∗𝐿𝑠

kg/s = kg/s

𝑄= 𝑚𝑓𝑢𝑒𝑙( 𝑞𝐻𝑉)

𝑄=𝑘𝑊=𝑘𝐽𝑠= 𝑘𝑔𝑠(𝑘𝐽𝑘𝑔)

kJ/s = kJ/s

𝜀= 𝑊𝑜𝑢𝑡𝑄= 𝑘𝑊𝑘𝑊

Thus efficiency has no units

*This answer seems to make sense because we know that two stroke engines in general have very low efficiencies. Similarly our 70’s chainsaw has very poor fuel economy and does not have the fuel economy subsystems that today’s chainsaws use.

Discussion:

This calculation is important to make, and take into consideration during the design process for a few reasons. In today’s economy and with gas prices as high as they are people are in general extremely concerned with fuel efficiency. A good way to obtain a fuel efficient product is to improve the engines efficiency. So when designing an engine, an engineer would want to make altercations and see how those altercations improved or negatively affected the engine’s efficiency.

We must also consider the fact that in our assumption we assumed all of the gas will be combusted. When in reality we will not use up all of the combustible gas and some will be lost, thus giving us a slightly smaller percentage efficiency than we have calculated.

Conversion of Physical Human Energy into Rotational Energy

In order to convert the physical human energy into rotational energy the flywheel, pull start, and engine must work together. The Four design factors influenced this subsystem design in the following ways:

Societal:

Safety is crucial for this subsystem. Engineers must consider the fact that humans will need to start the chainsaw manually. For a product that will start with high speed rotating sharp teeth that can rip through bone, safety precautions have to be considered. Upon starting the machine engineers must make the pull start easy enough for the user to do without hurting themselves, but it still must rotate the flywheel fast enough to start the machine. To compensate, design considerations were implemented such as the orientation of the pull start. The user is always pulling up and away from the teeth and the cord is located on the opposite side of the chain. The radius and springs and angle of the pulley are also specific in that it can take the force exerted by the human and increase that torque so that it is greater on the flywheel. During design, the engineer will take into consideration the average force that a 18-45 year old male can exert, given they will be the predominant users. Similarly, as soon as the machine is started the flywheel will begin to spin at high speeds and we must make sure that the consumer is not at any risk of these high rotating speeds so a safety cover is manufactured specifically to allow air flow and only air flow to enter into the fan but will not allow any material to get in or out.

Design Revisions

One design revision that we propose is to make all the outer casings, such as the flywheel cover, clutch cover, and engine guards, out of plastic. With the product being made in the 1970s, using and making plastic wasn’t very popular, easy or cost-efficient. Now that technology is much more advanced, and there are processes such as injection molding, using plastic for the outer casings would be much easier to make and much more economical. Also this would make the overall weight of the chainsaw much lighter and easier to handle for the consumer.Proposed Change

Image 37: Proposed Chainsaw Design

A Second design revision that we propose is to add handles that decrease vibration from the engine. This could be done by separating the handles from the engine by adding springs or rubber bushings or by adding rubber onto the handles themselves. Also, because our product was made 30 or more years ago rubber, much like plastics as mentioned above, were not easily made during this time. Making these design revisions will make the chainsaw more comfortable to use for the consumer and will help to prevent any hand, joint injuries do to its use.

Current Handle

Image 38: Current handle

Proposed Change

Image 39: Proposed Change

One Third design revision we propose would be made on the flywheel. It is clear to us that our flywheel is made of aluminum with a magnetic piece located on the side that was implanted during the die casting process. The flywheel has many fan blades on it in order to cool the engine. Since two of the fan blades on our flywheel have broken off, we propose that the flywheel be made of stainless steel with a high nickel content. Normally stainless steel is magnetic but since the flywheel has a magnetic piece attached, the material used to make the flywheel cannot be attracted to this magnetic piece. Using stainless steel with a high nickel content will drastically lessen its chances of becoming magnetized. Using stainless steel would cost more to make, but in the long run the part would last longer and the consumer would not have to replace it.

Current Flywheel with Broken Blades

Image 40 : Flywheel

Gate 4: Product Explanation

This portion of the project focuses on the reassembly of our chainsaw, and the revisions that can be made in order to improve our product. Below you will find a reassembly complexity scale, reassembly chart, and three design revisions made to our chainsaw.

Project Management: Critical Project Review

Cause For Corrective Action

General Problems and Resolutions

Since the last update, our group has been working very well together. We have successfully made it through a rough few weeks and can now focus more on finishing up the project. Our past communication issues have cleared up and we always check in with each other before scheduled meetings to make sure we will all be able to attend. The members of our group have also been much better about getting to meetings on time and even if members are a few minutes late, other members start to work on things that need to be accomplished. Members have also been much better with getting work done and not getting distracted as mentioned before. We have been much more productive during meetings and have also tried to get a majority of the work for each gate done as early as possible and not wait until the last minute. The addition of our Technical Expert as a Co-Manager has been working out rather smoothly. This has ensured that each portion of the assignment gets done and that work is split up evenly between members. We have also made sure to have another member of the group read through portions of the assignment that we have done individually to make sure that it can be understood.

Reassembly Review

After we dissected our product for a second time, and made certain parts were kept together, reassembly went rather smoothly, but there were a few issues that we came across. As mentioned in Gate 3, there were many screws, nuts, bolts, etc. that we were unsure about their location. Finding where these miscellaneous fasteners were located was the hardest part of reassembly, but in the end we managed to find out where each and every fastener belonged. One other challenge we came across during reassembly was that after we had put a group of parts back together, we had realized that we had forgotten a piece and we had to take apart what we had just done and place the forgotten part back into the product. Two hours and many forgotten parts and pieces later, we had completely reassembled our product.

Future Issues/Solutions

Fall break wasn’t as much of an issue as we had expected. Our group met at the normal Tuesday meeting time and got a considerable amount of work accomplished, even though one member was still out of town. We are definitely expecting time management issues with Gate 5, due to the fact that it is due after many finals. Trying to finish the final gate and studying for all our final exams will be very tough. To deal with this time issue we will first need to lay out each others finals schedules so we can point out time slots that all of us are free. Due to our very different/busy study schedules we will not have a large enough time gap to complete the entire gate together, thus we will plan two meetings. The first meeting we will use the time to lay out a plan and assign work to be done at home when convenient for the individual, but finished before the second meeting. The second meeting will allow us to check over each others work and get the gate up on the wiki.

Product Archaeology: Product Explanation

Reassembly Complexity Scale

Below we define our complexity scale. This will be used throughout the reassembly process to give a sense of how time consuming each step is, along with the complexity of the components connections.

Figure 19: Reassembly Complexity Scale

Product Reassembly

The following steps should be taken while reassembling the chainsaw. Again many components have multiple connections, therefore the reassembly process is far more difficult than the dissection process. Please view the labeled photo for each step in order to avoid confusion.

Step

Components Being Assembled

Tool Needed

Directions

Time Required

Difficulty

Image

1

Center Shaft/ Right Casing

None

Insert clutch side of the center shaft(side with larger threads) into the right casing (side that lacks oil and gas ports).

30-60 sec

Image 41: Assembly Process Step 1

2

Trigger/ Connecting Rod/Left Casing

None

Mount the trigger on its designated rod built into the right casing. (Note: Connecting rod should navigate towards the left side of the product)

15-30 sec

Image 42: Assembly Process Step 2

3

Left Casing

Flat HeadScrew Driver

Attach left casing to right casing enclosing the trigger system, and center shaft between the two casings. Using the flat head screw driver, tightly screw all four screws into place.

2-4 mins

Image 43: Assembly Process Step 3

4

Piston Ring

None

Place the piston ring in the groove that runs around the circumference of the piston. Ensure that the ring does not protrude from the contour of the piston to ensure the following step will run smoothly.

2-4 mins

Image 44: Assembly Process Step 4

5

Engine block

Adjustable Wrench

Carefully slide the piston into the cylinder of the engine block. Once the piston is in, secure engine block to the main casing using four nuts and bolts. An adjustable wrench will be needed in order to fasten the bolts. (Note: To ensure engine block is not upside down, exhaust outlet should be exposed, refer to Image 32.)

2-4 mins

Image 45: Assembly Process Step 5

6

Carburetor/Intake

Flat head Screw Driver

Place The intake on top the carburetor and fasten together using two screws and the flat head screw driver

1 min

Image 46: Assembly Process Step 6

7

Trigger/fuel lines/ Choke switch

None

Flip the chainsaw right side up. Latch the trigger system to the intake.Place fuel lines in their appropriate position on the carburetor. Latch the choke switch to the intake.

4-7 mins

Image 47: Assembly Process Step 7

8

Carburetor/Intake

Flat Head Screw driver

Mount the Carburetor/Intake system to the top of the chainsaw. Drive 2 screws into the frame of the chainsaw using a Flathead screw driver.

1 min

Image 48: Assembly Process Step 8

9

Heat Guard

None

Flip chainsaw upside down. Place heat guard on top of the engine bock (refer to image 36).

5-10 secs

Image 49: Assembly Process Step 9

10

Exhaust

Flat Head Screw Driver

Fasten exhaust on top of heat guard using four screws and a flat head screw driver. (Note: One screw must be screwed on the inside of the exhaust as labeled in image 37)

1-2 min

Image 50: Assembly Process Step 10

11

Exhaust Cover

Flat Head Screw Driver

Attach exhaust cover using a flat head screw driver and four screws located on all four corners of the cover.

1-2 min

Image 51: Assembly Process Step 11

12

Magneto

Flat Head Screw Driver

Attach the Magneto to the engine block using the flat head screw driver and two screws.

1-2 min

Image 52: Assembly Process Step 12

13

Spark-Plug

Spark-Plug Socket Wrench

Screw the spark-plug into its designated hole on the engine block. Fasten tightly using the spark plug socket wrench.

30-60 secs

Image 53: Assembly Process Step 13

14

Metal Spacer

Flat head Screw Driver

Slide metal spacer over center shaft and two bolts as seen in image 41. Fasten spacer using the flat head screw driver and two screws.

1-2 min

Image 54: Assembly Process Step 14

15

Sprocket

None

Slide washer on the center shaft, then proceed to slide the sprocket on the center shaft, same side as the muffler.

30-60 secs

Image 55: Assembly Process Step 15

16

Clutch

Vise Grips

Slide the clutch on the center shaft, which should fit right inside sprocket.To fasten, secure opposite side of center shaft with the vise grips and turn clutch COUNTERCLOCKWISE.

4-7 min

Image 56: Assembly Process Step 16

17

Engine Guard/ On-Off Switch

Flat Head Screw DriverAdjustable wrench.

Take the threaded on/off switch and fit into Engine guard (slot that says on/off). Fasten it with a nut and adjustable wrench. Now fasten engine guard to casing with screws. Note: Before engine guard is fully fastened, make sure you connect the spark plug to the magneto, and the wire is inside of the engine guard.

2-3 mins

Image 57: Assembly Process Step 17

18

Fly Wheel

Adjustable wrench.

Slide Flywheel onto the center shaft opposite of the clutch. Secure the flywheel using an adjustable wrench, and a nut.

30-60 secs

Image 58: Assembly Process Step 18

19

Fly Wheel Cover

Flat Head Screw Driver

Mount the flywheel cover to the main casing over the flywheel. Secure using a flat head screw driver and 4 screws.

1-2 mins

Image 59: Assembly Process Step 19

20

Handle Bar

Flat Head Screw Driver

Place the handle bar in its designated groove located on the bottom of the chainsaws frame. Secure using a flat head screw driver and three screws.

1-2 mins

Image 60: Assembly Process Step 20

21

Chain Bar

None

Mount the chain bar as seen in image 48

10-20 secs

Image 61: Assembly Process Step 21

22

Clutch Cover

Adjustable Wrench

Mount the clutch cover over the clutch. Secure using an adjustable wrench and two nuts.

1-2 mins

Image 62: Assembly Process Step 22

23

Intake Cover

Flat Head Screw Driver

Place the intake cover over the carburetor/intake system. To fasten apply downward pressure on center bolt and turn once.

20-30 secs

Image 63: Assembly Process Step 23

Challenges Faced

Due to our knowledge of the product, our reassembly went quite smooth. There were two challenges that the group faced. They are discussed below.

Challenges were faced while attempting to install the trigger system and the engine block. At first, we put the trigger system on backwards. This issue was resolve by trail and error. A note was added to the reassembly chart in order to avoid confusion in the future.

Similar challenges arose while attempting to install the engine block. At first we mounted the engine block upside-down. This issue was also resolve by trail and error. A note was added to the reassembly chart to avoid future confusion.

Original Assembly

This product was originally assembled in some sort of assembly line process. It is reasonable to assume that this product was mass produced, and in order to hand assembly these chainsaws a large amount of labor would be required. This product was assembled in a way in which it can be dissected in the future. The reason it was made this is due to the fact that inner components can become displaced or broken, and the chainsaw will need to be opened in order to fix or replace parts in the future.

Assembly vs. dis-assembly

The assembly process was basically the dis-assembly process in reversed order. As you can image putting something back together is a little more difficult than taking it apart, as that was the case with our chainsaw. The reason it was a little more difficult was because of the fact that we had to implement the connection of each component properly, whereas for the dis-assembly you are not very concerned with these connection because they are already implemented.

System Design Revisions

Main Casing Revision

Image 64: Current Chainsaw Design

Current Design:
As seen in image 51, the current design of our chainsaw has full aluminum body. This current design causes the chainsaw to be much heavier then it needs to be.

Image 65: Proposed Chainsaw Design

Proposed Design:
Our Proposed design change is to switch the outer body casing of the chainsaw to plastic as opposed to the current aluminum body (see image 52). The motivation for this design change is driven by economic and societal factors. The economic factor behind this change is a reduced price in the overall cost of the product for the consumer. With this change you lower the price for the consumer, which will increase the market for our product. The societal factor behind this change is a reduced weight in the overall product. The original design caused the chainsaw to be quite heavy and as a result may have scared users off from using the chainsaw. With a lighter body we can increase the range of people who are able to use the chainsaw as well as create a safer product due to the reduction in weight.

Change in Durability Factors:
By changing the casing to plastic some might say plastic breaks easier. This is true however, we will similarly considered the societal and economic factors of this revision which is also safety and consumer cost. Dropping the chainsaw with the current aluminum body will easily dent. A dent to the casing in the right spot could directly affect the functionality of the overall product. An example would be a dropped chainsaw produces a dent on the flywheel cover (common). This dent could be deep enough to touch the spinning flywheel which would produce an extremely dangerous scenario, given high speed metal to metal contact(sparks), inside a gasoline engine. Thus, a replacement flywheel cover will be needed anyway.This scenario or anything like it will never happen with a plastic casing. We can conclude by saying plastic is safer when encountering a break and cheaper to replace if needed due to its cheap material as compared to aluminum.

Stress Strain: Plastic vs. Aluminum
We also investigated whether or not plastic was durable enough to withstand the chainsaws constant High Vibration Levels. As you can see in Figure A: we show the stress strain curve of a brittle material such as aluminum. When the material is put under too much stress such as high vibrations and heat, the material will reach its yield point and crack. As for an elastic material such as plastic, you can see in Figure B: that when the material reaches its yield point it expands and contracts before cracking, when vibrations cease the material will then go back to its normal structure. This expansion and contraction will also decrease vibrations on the user. In conclusion we find that plastic will give us a more durable, and more comfortable product.

Future Plans:
The proposed design revision will undoubtedly come with several un-answered questions that will have to be examined further before the changes are implemented. The first impact that must be looked at is the balance that will surely be altered once the outer casing is changed it may be necessary to move around several of the internal components if it is discovered that the balance is drastically altered to a point which causes the product to be unsafe. Another impact that must be viewed is the consumers demand for a lighter chainsaw made of plastic as opposed to the original design however we are fairly certain that the lighter chainsaw will be well received since almost all modern chainsaws are composed of a plastic body.

Chain/Bar Safety Revision

Current Design:
The current design of the chainsaw has a simple chain and guide bar system that allows for the proper functionality of the chainsaw, which is to remove material (Image 66 is our stock chain-bar).

Image 66: Chain bar

Proposed Design:
We propose to incorporate an entirely new chain/bar safety system including features such as: a chain brake, chain catcher, a bar tip protector, or a kickback reducing chain that will increase the safety of the overall product.

Chain Brake – applies a steel brake band around the clutch drum as shown in Image 68 and Image 67 #1 shows the location of the chain brake. This steel brake band band stops the chain when the machine is a partial throttle. In between cuts and during starting there will be no wild chain movements which is commonly a hazardous problem for older chainsaws such as ours.

Kickback Reducing Chain- There are many styles and types of chains that can be put onto our chainsaw each with a distinct function.Some of these chains include a self lubricating, self sharpening,low vibration, and "Ripping" chains. These chains even though they improve functionality are too specific to the user to set as the default chain. We propose a this anti kickback chain because all users will be interested in safety. This chain consists of a guard(side) links in front of each cutter link. Which reduces the tendency of the leading edge of the depth gauge to snag on small-diameter objects or cut through medium sized timber with ease. Depth gauge(railer), a small steel protuberance in front of each cutting tooth. The difference in height between the leading cutting edge and the depth gauge determines the thickness of the wood chip taken by the cutter, which gives the user better performance and minimized kickback if set correctly. Image 69 points out each component of the new chain.

Chain Catcher- The chain catcher literally catches the chain if the machine kicks back and snaps the chain or if it simply pops off (Image 70 shows chain catcher. Image 67 #2 shows location.) This is important because when the chain is moving at very high speeds, if it does pop off it can be considered deadly shrapnel.

Image 70: Chain catcher

Bar tip Protector- This is a protection device that will not allow the chain to cut at the tip of the chain arm (Image 58).
.

Image 71: Bar tip Protector

Motivation for Revision:

A common problem that older chainsaw products face, such as ours, is chain kickback. Kickback may occur when the rotating tip or nose of the chain touches an object, or when the wood closes in and pinches the chain [11]. When this happens the chain will seize and transfer the energy through the user, putting the user in a very dangerous situation. A common goal for engineers when designing modern chainsaws is to minimize this kickback thus minimizing safety hazards, and minimized safety hazards maximizes sales.

Societal Factors- For such a high risk product that has the power and material to harm a user greatly in the case of an accident, safety is a major concern during design. Roughly 28,000 chainsaw-related injuries are reported annually, most commonly being neck, shoulder, and major back injuries [10]. Working with chainsaws is known to be very risky and sometimes viewed as a professional skill. This is why many homeowners decide to leave it to the professionals and often never attempt chainsaw projects themselves. Similarly even professionals are forced out of their profession because they can’t take such high risks. Incorporating safety features that can greatly minimize/eliminate the risk factor, will allow the husband of a concerned wife to get a chainsaw so he can do a little home improvement himself and the professional can be confident that he is not putting himself at risk everyday when he goes to work.

Some extra manufacturing processes will be required to implement this revision. However, these processes will be of the simplest (traditional die casting) and fairly inexpensive. Each extra piece will require extra (metal) material which will cost extra money, although these pieces are so small the extra material will be minuscule, not even 1% of the current material needed for the overall product. As for design modifications for implementation, there will be none. Each of these pieces are designed with convenient location in mind so that the extra piece will not compromise the functionality of the chainsaw, however sizing will be required for specific chainsaws.

Future Plans:
Before implementing these design changes we will have to investigate cost of revisions, design and material production, and consumer information and preferences. These revisions will certainly increase cost of the product. We must investigate how much and whether or not this cost should be passed down to the consumer or if the company should absorb a percentage of the cost. Although the cost will increase, safety is generally the more important factor to a user. Thus, we must make sure that the design revisions do not impact ease of use and/or functionality. Professionals will need to try the product out and give reviews. No professional will want to pay more for a product that makes it more difficult for them to use, which can often be the case when incorporating safety features. A safer model chainsaw that improves ease of use will be a much desired product.

Anti Vibration System Revision

Current Design:
Currently the only thing on our chainsaw protecting the user from vibration is a small amount of rubber covering the metal handles as shown in image 72. Since it was manufactured in the 1970s many anti vibration techniques had not been developed yet.

Image 72: Current handle

Proposed Design:
Today’s chainsaws are normally divided into two sections. The first section can be considered the chain and the engine, these two components vigorously vibrate while the machine is at full throttle. The second section can be considered the handles and the controls. We propose to separate these two sections of our chainsaw. Separating the two sections will allow the vibrations of the engine(section 1) to not transfer to the handle(section 2)thus, not transfer to the user. In order to have two independent sections that work as one something has to hold them together, but hold them in a way that the vibrations do not transfer. To do this, (soft) rubber bushings will be used such as the one seen in image 73 and (stiff) metal springs as shown in image 74. Soft bushings so the engines small yet powerful vibrations can each be absorbed but stiff springs so the weight of the engine is supported. These will act as a suspension such as that you would see on a bicylce.
Motivation for this design this revision is mostly impacted by societal factors. Reducing the vibration will make the chainsaw much more comfortable to use and will allow the consumer to use the product for a much longer time period. This system revision will also drastically lessen the chance of injury due to excessive vibrations.

Image 73: Location Rubber bushing between the frame and the interior casing

Image 74: Location Metal spring isolates engine block

Future Plans:
Although these additions come standard on current chainsaws, if they were to be added to our chainsaw, research would still need to be conducted. Testing would need to be performed to see the perfect level of stiffness of the bushings and springs. An analyses of how much adding these additional parts would impact the overall cost for the company and for the consumer will be constructed. Also, research would need to be conducted to find out how the two sections would be arranged and if it would impact the current location of any specific parts. It would also be beneficial to conduct a consumer study to find the maximum level of vibration that allows the user to comfortably handle the chainsaw.